Occlusion-crossing devices, imaging, and atherectomy devices

ABSTRACT

A catheter device for crossing occlusions includes an elongate body, a central lumen extending within the elongate body from the proximal end to the distal end, a rotatable tip at the distal end of the elongate body, and an OCT imaging sensor. The rotatable tip is configured to rotate relative to the elongate body. The OCT imaging sensor includes an optical fiber coupled with the rotatable tip and configured to rotate therewith. A distal end of the elongate body includes one or more markers configured to occlude the OCT imaging sensor as it rotates. A fixed jog in the elongate body proximal to the distal end of the catheter positions the distal end of the catheter at an angle relative to the region of the catheter proximal to the fixed jog and is aligned with the one or more markers on the elongate body.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/434,758, filed on Feb. 16, 2017, titled “OCCLUSION-CROSSING DEVICES,IMAGING, AND ATHERECTOMY DEVICES,” now U.S. Pat. No. 11,134,849, whichis a continuation of U.S. patent application Ser. No. 14/171,583, filedon Feb. 3, 2014, titled “OCCLUSION-CROSSING DEVICES, IMAGING, ANDATHERECTOMY DEVICES,” now U.S. Pat. No. 9,572,492, which is acontinuation of U.S. patent application Ser. No. 13/433,049, filed onMar. 28, 2012, titled “OCCLUSION-CROSSING DEVICES, IMAGING, ANDATHERECTOMY DEVICES”, now U.S. Pat. No. 8,644,913 which claims priorityto U.S. Provisional Patent Application No. 61/548,179, filed on Oct. 17,2011 titled “OCCLUSION-CROSSING DEVICES, IMAGING, AND ATHERECTOMYDEVICES” and U.S. Provisional Patent Application No. 61/468,396, filedon Mar. 28, 2011, titled “OCCLUSION-CROSSING DEVICES, IMAGING, ANDATHERECTOMY DEVICES,” each of which is herein incorporated by referencein its entirety.

This patent application may be related to one or more of the followingpending patent applications: U.S. patent application Ser. No.12/689,748, filed Jan. 19, 2010 and titled “GUIDEWIRE SUPPORT CATHETER”,now U.S. Pat. No. 8,696,695; U.S. patent application Ser. No.12/108,433, filed Apr. 23, 2008 and titled “CATHETER SYSTEM AND METHODFOR BORING THROUGH BLOCKED VASCULAR PASSAGES”, now U.S. Pat. No.8,062,316; U.S. patent application Ser. No. 12/272,697, filed Nov. 17,2008 and titled “DUAL-TIP CATHETER SYSTEM FOR BORING THROUGH BLOCKEDVASCULAR PASSAGES”, Publication No. US-2010-0125253-A1, now abandoned;U.S. patent application Ser. No. 12/829,277, filed Jul. 1, 2010 andtitled “ATHERECTOMY CATHETER WITH LATERALLY-DISPLACEABLE TIP”, now U.S.Pat. No. 9,498,600; U.S. patent application Ser. No. 12/829,267, filedJul. 1, 2010 and titled “CATHETER-BASED OFF-AXIS OPTICAL COHERENCETOMOGRAPHY IMAGING SYSTEM”, now U.S. Pat. No. 9,125,562; U.S. patentapplication Ser. No. 12/790,703, filed May 28, 2010 and titled “OPTICALCOHERENCE TOMOGRAPHY FOR BIOLOGICAL IMAGING”, Publication No.US-2010-0305452-A1; and U.S. patent application Ser. No. 12/963,536,filed Dec. 8, 2010 and titled “DEVICES AND METHODS FOR PREDICTING ANDPREVENTING RESTENOSIS”, now U.S. Pat. No. 8,548,571. Each of thesepatent applications is herein incorporated by reference in its entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD

Described herein are catheters and specifically, catheters that mayinclude a rotating distal tip having both a directional cutting elementand an OCT imaging sensor, an inner lumen for a guidewire extending thelength of the catheter, and an optical fiber that is configured to windand unwind within the catheter as the OCT imaging sensor at the distalend rotates. The catheters described herein may be configured as one ormore of: guidewire support and/or placement catheters, imagingcatheters, atherectomy catheters, chronic total occlusion crossingcatheters, and hybrid support/placement catheters with imaging and/oratherectomy features. Methods of using the catheters described hereinare also provided.

BACKGROUND

Peripheral artery disease (PAD) affects millions of people in the UnitedStates alone. PAD is a silent, dangerous disease that can havecatastrophic consequences when left untreated. PAD is the leading causeof amputation in patients over 50 and is responsible for approximately160,000 amputations in the United States each year.

Peripheral artery disease (PAD) is a progressive narrowing of the bloodvessels most often caused by atherosclerosis, the collection of plaqueor a fatty substance along the inner lining of the artery wall. Overtime, this substance hardens and thickens, which may interfere withblood circulation to the arms, legs, stomach and kidneys. This narrowingforms an occlusion, completely or partially restricting flow through theartery. Blood circulation to the brain and heart may be reduced,increasing the risk for stroke and heart disease.

Interventional treatments for PAD may include endarterectomy and/oratherectomy. Endarterectomy is surgical removal of plaque from theblocked artery to restore or improve blood flow. Endovascular therapiessuch as atherectomy are typically minimally invasive techniques thatopen or widen arteries that have become narrowed or blocked. Othertreatments may include angioplasty to open the artery. For example, aballoon angioplasty typically involves insertion of a catheter into aleg or arm artery and positioning the catheter such that the balloonresides within the blockage. The balloon, connected to the catheter, isexpanded to open the artery. Surgeons may then place a wire mesh tube,called a stent, at the area of blockage to keep the artery open.

Such minimally invasive techniques (e.g., atherectomy, angioplasty,etc.) typically involve the placement of a guidewire through theocclusion. Using the guidewire, one or more interventional devices maybe positioned to remove or displace the occlusion. Unfortunately,placement of the guidewire, while critical for effective treatment, maybe difficult. In particular, when placing a guidewire across anocclusion, it may be difficult to pass the guidewire through theocclusion while avoiding damage to the artery. For example, it is oftendifficult to prevent the guidewire from directing out of the lumen intothe adventitia and surrounding tissues, potentially damaging the vesseland preventing effective treatment of the occlusion.

If imaging is used to assist in placement of guidewires for treating PAD(including treatment of chronic total occlusion), fluoroscopy istypically used to visualize the location of the lumen of the vessel withrespond to the guidewire. However, it would be particularly beneficialto visualize within the lumen of a vessel as the guidewire is placed,both to identify regions for effective therapy as well as to preventdamage to surrounding tissue.

A significant body of scientific and clinical evidence supportsatherectomy as a viable primary or adjunctive therapy prior to stentingfor the treatment of occlusive coronary artery disease. Atherectomyoffers a simple mechanical advantage over alternative therapies.Removing the majority of plaque mass (e.g., debulking) may create alarger initial lumen and dramatically increases the compliance of thearterial wall. As a result, stent deployment is greatly enhanced.

Additionally, there are advantages related to the arterial healingresponse when selecting atherectomy as a treatment option. Whencircumferential radial forces are applied to the vasculature, as in thecase of angioplasty or stenting, the plaque mass is displaced, forcingthe vessel wall to stretch dramatically. This stretch injury is a knownstimulus for the cellular in-growth that leads to restenosis. Byremoving the disease with minimal force applied to the vessel andreducing the plaque burden prior to stent placement, large gains inlumen size can be created with decreased vessel wall injury and limitedelastic recoil, all of which have shown to translate into better acuteresults and lower restenosis rates.

Traditional atherectomy devices have been plagued by a number ofproblems, which have severely limited market adoption. These challengesinclude the need for large access devices, rigid distal assemblies thatmake control and introduction challenging, fixed cut length,unpredictable depth of cut, insufficient tissue collection and removal,and complex operation. The systems and devices described herein mayovercome these hurdles and offer physicians a safe, reliable, and simplecutting system that offers the precision required in eccentric lesions,various disease states, and tortuous anatomy.

Despite the potential to improve restenosis rates associated withangioplasty and stenting in the coronary and peripheral vasculature,atherectomy is not commonly performed. The primary reason for thislimited use is the cost, complexity, and limited applicability ofcurrently available devices. Many designs are unable to treat the widerange of disease states present in long complex lesions; luminal gain isoften limited by the requirement of the physician to introduce multipledevices with increased crossing profiles; tissue collection is eitherunpredictable or considered unnecessary based on assumptions regardingsmall particle size and volumes; and optimal debulking is either notpossible due to lack of intravascular visualization or requires verylong procedure times. Based on these limitations, current devices arelikely to perform poorly in the coronary vasculature where safety andefficacy in de novo lesions, ostials, and bifurcations continue to posegreat challenges.

Previously, atherectomy devices focused on macerating or emulsifying theatherosclerotic plaque such that it may be considered clinicallyinsignificant and remain in the blood stream or aspirated proximallythrough small spaces in the catheter main body. The reliability of thesedevices to produce clinically insignificant embolization has beenquestioned when not aspirated through the catheter to an externalreservoir. Aspiration requires a vacuum be applied to a lumen or annularspace within the catheter to remove emulsified tissue. In early clinicalevaluations of aspiration, the presence of negative pressure at thedistal working assembly cause the artery to collapse around the cuttingelement causing more aggressive treatment, dissections and/orperforations. In addition, the option for post procedural analysis ofany removed disease is extremely limited or impossible. Atheromed,Pathway Medical and Cardio Vascular Systems, Inc. are examples ofcompanies working on such product designs.

Other atherectomy devices include the directional atherectomy devicessuch as those developed by Devices for Vascular Intervention and FoxHollow. These catheters use cupped cutters that cut and direct thetissue distal into a storage reservoir in the distal tip of the device.This approach preserves the “as cut” nature of the plaque but requireslarge distal collection elements. These large distal tip assemblies canlimit the capabilities of the system to access small lesions and createadditional trauma to the vessel.

Currently available atherectomy devices also do not include, and arepoorly adapted for use with, real time image guidance. Physicianpractice is often to treat target lesion as if they contain concentricdisease even though intravascular diagnostic devices have consistentlyshown significantly eccentric lesions. This circumferential treatmentapproach virtually ensures that native arterial wall and potentiallyhealthy vessel will be cut from the vasculature.

In light of the needs described above, occlusion crossing catheterdevices, atherectomy catheter devices, imaging catheters (includingimaging guidewire placement devices and imaging atherectomy devices) andsystems and methods for using them are described herein in order toaddress at least some of the concerns described and illustrated above.

SUMMARY OF THE DISCLOSURE

The present invention relates to catheters having a rotating distal tipregion that includes an OCT imaging sensor and may include one or moretissue dissecting elements. These catheters may also include a centralpassage or lumen that opens distally, extending along the length of thecatheter body, that may be used to pass a guidewire. In general, thecatheters described herein may be configured as: (1) guidewiresupport/placement catheters; (2) support/placement imaging catheters;(3) occlusion crossing catheters (4) occlusion crossing imagingcatheters; (5) atherectomy catheters; and (6) atherectomy imagingcatheters. Any of these catheter variations may include one or more ofthe elements described herein, and any of these catheter variations maybe used to treat a disorder, particularly peripheral artery disease.Systems including any of these catheters are also described. Forconvenience, in the description below, these catheters may be referredto as occlusion crossing catheters. It is to be understood that any ofthe catheters described herein may be configured as occlusion crossingcatheters.

In general, a catheter may include a flexible elongate body, a proximalhandle (or handle region), and a distal rotating tip. The distal tip mayhave a corkscrew-like rotating tip which is configured to rotate toenhance forward motion (e.g., at low rates of rotation) without cuttingor drilling through the tissue. Rather than drilling, the tip may beconfigured to prevent or reduce static friction, avoiding damage to theluminal walls of the vessel and preventing the tip from passing throughthe adventitia.

The tip may be configured to rotate at very low speeds (e.g., less thanabout 300 revolutions/min, less than 100 rev/min, less than 50 rev/min,less than 30 rev/min, e.g., between about 1 and about 30 rev/min, etc.)at a constant or variable rate. In many variations, particularly but notnecessarily those including an imaging modality (e.g., OCT) with animaging sensor affixed to the rotating tip, the tip may rotateautomatically both clockwise and counterclockwise, alternately. Forexample, the device or system may be configured to rotate the distal tipfirst clockwise, then counterclockwise. The clockwise andcounterclockwise rotations may be performed continuously for apredetermined number of revolutions or partial revolutions, such as morethan one revolution (e.g., approximately 2 revolutions, 2.5 revolutions,3 revolutions, 5 revolutions, 8 revolutions, 10 revolutions, 12revolutions, 20 revolutions, 50 revolutions, 100 revolutions, or anynumber of revolution between 1 and 500, including fractions ofrevolutions). In some variations, the number of rotations is notpredetermined, but may be based on timing or on feedback from thecatheter or system. For example, the distal tip (and therefore the OCTimaging sensor) may be rotated in a first direction until a tension orresistance threshold is reached, then rotated in the opposite directionuntil a tension or resistance threshold is reached in that direction.This process may then be repeated.

Any of the catheters described herein may include one or more tissuedissecting cutting edges on the rotating distal tip. In some variations,the forward edge of the catheter includes one or more helical edges,which may be referred to as wedges. The helical edges may be arranged atthe distal end of the device. The edge may have a small diameter,particularly as compared with the ultimate diameter of the device. Theseedges may be sharp, rough, or otherwise dissecting.

Any of the catheter variations described herein may include a centrallumen through which a guidewire may be passed for placement across anocclusion using the device. The central lumen typically extends alongthe length of the device from the proximal end or a region distal to theproximal end, to the distal end of the catheter. Thus, the catheter mayinclude a distal opening. This central lumen may be referred to as aguidewire lumen. In some variations, the device is configured to passthrough a lesion or occlusion (or an occluded region or regions of avessel) to position the catheter beyond the occlusion before a guidewireis passed through the catheter. Alternatively, the guidewire may behoused or held within the lumen while the device is advanced through theocclusion or occluded region of a vessel, such as an artery, vein, orduct, for example a peripheral artery, vein, or bile duct.

In general, the catheters described herein are configured to applyoptical coherence tomography (OCT) to image the tissue. Thus, thecatheters described herein can include an imaging sensor, such as an OCTimaging sensor. An OCT imaging sensor may include the distal end of anoptical fiber and a mirror for directing light in/out of the opticalfiber. The optical fiber may be affixed to the distal tip structure. Theimaging sensor may be oriented to image the vessel ahead of the device,perpendicular to the device, and/or behind the device tip. The mirror orreflector may be used to direct the light path entering and exiting theend of the optical fiber to fix the imaging direction for the device.For example, the optical fiber and mirror may be fixed to the rotatingdistal tip region and may be embedded in a transparent or translucentmedium (including transparent cement or other fixative).

An optical fiber of the OCT system can be attached only to the rotatingdistal tip and at a proximal end but be free to move within the devicelumen. As the distal end or tip of the device rotates, the optical fibermay wrap and unwrap around the inner lumen as the distal end/tip isrotated clockwise and counterclockwise. Thus, the length of the opticalfiber extending from this affixed region at the rotatable distal tip tothe proximal end of the catheter is loose within the catheter body andfree to wind/unwind around the catheter body. The inventors havediscovered that this loose arrangement of the optical fiber createsadvantages compared to systems in which an optical fiber is held alongits length or prohibited from off-axis winding, including ease ofconstruction and enhanced catheter flexibility. Thus, any of thecatheters described herein may be adapted to allow and control thewinding/unwinding of the optical fiber within the catheter, and theoptical fiber may be located within the catheter in an off-axisposition.

In some variations, the distal end of the device is steerable, pre-bent,or both. For example, the distal end may be biased or curved at an angleoff the axis of the shaft. In some variations, a control member (e.g.,tendon or other actuator) may be used to control the shape of the distalend. In some variations the catheter includes a prebiased shape or fixedjog so that the distal end of the device (e.g., the rotatable distaltip) forms an angle with the region of the catheter's elongate bodyimmediately proximal to the fixed jog. A fixed jog may help withsteering and navigation of the catheter. The jog may be in a plane thatis in-line with one or more fiduciary markers that are visible byfluoroscopy or other imaging modality (e.g., ultrasound, etc.).

Any of the catheters configured for imaging described herein may also beconfigured to enhance the imaging by flushing or otherwise clearing theimaging sensor region so that it may image the vessel wall(s). Forexample, the catheter may include one or more flush or fluid deliveryports for providing a flushing fluid to clear the visualization pathwayfor the device. Saline or other flush fluids may be released from thefluid delivery ports to clear the field of view. Flushing may beachieved at a sufficient fluid flow rate to clear help clear the fieldof view (e.g., by flushing away red blood cells or other material thatmay inhibit visualization of the vessel walls). The flush portopening(s) at the distal end may be positioned and sized to minimize theamount of fluid (or the fluid flow rate) need to flush the imagingfield. Thus, a flush port may be located near the imaging sensor. Forexample, a flush port may be less than 2 mm from the imaging sensor.Flushing may be controlled manually or automatically.

In some variations, the catheter may have an outer protective housingalong the elongate length extending between the distal tip region andthe proximal handle or connector region. A space within the outerprotective housing and an inner lumen may be referred to as the outerlumen or outer lumen region. An inner lumen, which may be referred to insome variations as a guidewire lumen, may be located within the outerlumen and used to pass the guidewire through the elongate length of thedevice. The inner lumen may be formed by an internal housing extendingalong the length of the device. The space between the outer protectivehousing and the inner lumen may also be referred to as the device lumen.In catheter variations including an optical fiber for imaging, theoptical fiber may be housed within the device lumen/outer lumen.Further, in devices including flushing, the flushing fluid can flowthrough the outer lumen.

Also described herein are catheters including one or more expandableand/or inflatable (e.g., balloon) elements. The inflatable element(s)may be used to help center the distal end of the device within the lumenof the device, helping to prevent the tip of the device from passingthrough the adventitia. The inflatable member could also be used tolimit or prevent the flow of a fluid that would normally block the fieldof view. In some variations, the expandable/inflatable region may belocated near the distal tip of the device, which may include a rotatingdistal tip/end region.

Also described herein are catheters configured as atherectomy cathetersthat may also include imaging. For example, describe herein areatherectomy catheters that are side-facing/side-opening and configuredto cut occlusive material from a vessel using a circular cutter than canbe rotated or oscillated to cut the tissue. Tissue cut in this mannermay be stored within the body of the device. The tissue may bemasticated or ground up as it is removed.

Specific example of catheters, and particularly occlusion crossingcatheters that may be used to place a guidewire across an occlusion, areprovided below.

Described herein are catheter devices for crossing chronic totalocclusions that include: an elongate body; a guidewire lumen extendingwithin the elongate body from a proximal end of the elongate body to adistal end of the elongate body; a rotatable tip at the distal end ofthe elongate body and configured to rotate relative to the elongatebody; and an OCT imaging sensor comprising an optical fiber coupled withthe rotatable tip and configured to rotate therewith, wherein theoptical fiber is configured to wrap around the central lumen within theelongate body as the rotatable tip rotates.

These catheter devices may also include a drive mechanism configured tocontinuously rotate the rotatable tip alternately clockwise thencounterclockwise. For example, the drive mechanism may be configured torotate the rotatable tip at between about 1 and about 100 rotations perminute (rpm), between about 30 and about 60 rpm, or greater than 100rpm.

A catheter may be configured so that the number of rotations clockwiseand counterclockwise is limited. For example, the number of rotationsclockwise may be less than 15 rotations before switching to rotatecounterclockwise another 15 rotations, then repeating this pattern ofrotation. In some variations, the number of clockwise/counterclockwiserotation is between about 1 and about 200, between about 1 and about100, between about 1 and about 50, between about 1 and about 20, etc.

In some variations, the OCT imaging sensor is configured to emit energyperpendicular to a longitudinal axis of the catheter device. Thus, theregion of the body (including the body lumen) immediately outside of thecatheter may be imaged. Because OCT may provides images of structureswithin the tissue, the tissue forming and surrounding the lumen may beimaged. This information may be used to guide the catheter, and/or toconfirm when an occlusion has been reached or crossed.

As mentioned, the rotatable distal tip may comprise a helical blade edgeor wedge. In some variations the helical wedge comprises a substantiallysmooth, curved outer surface that presents an atraumatictissue-contacting surface when rotated in a first direction (e.g.,clockwise) and that further presents a tissue dissection and/or sharp orrough tissue-cutting surface when rotated in an opposite direction tothe first direction (e.g., counterclockwise).

In any of the variations described herein one or more imaging markers(e.g., fiducial markers) may be included to help orient, and guide theoperation of the device, including positioning the device within thebody. A marker may be a radiopaque material (e.g., a metal) that can beseen in high contrast during fluoroscopy) or a material that reflexes orabsorbs optical beams from the OCT system (e.g., metal, dense polymer,carbon powder). In variations of the catheter including a fixed jog, thefixed jog may act as a marker, or in conjunction with a marker, to aidin steering the catheter device. In some variations, the elongate bodyincludes at least one marker configured to obstruct imaging from the OCTsensor at least once per rotation of the rotatable tip. More than onemarker may also be used (e.g., three markers).

In some variations the device includes a driveshaft that is concentricto the central lumen (e.g., surrounds the central lumen) so that thecentral lumen extends through the driveshaft. The driveshaft typicallyrotates the rotatable distal tip.

In general, the imaging sensor may be proximal to (though near) orincorporated within the distal tip. For example, the distal end of therotatable tip may be less than 3 mm from the imaging sensor.

Also described herein are catheter devices for crossing occlusions, thedevice comprising: an elongate body; a central lumen extending withinthe elongate body from a proximal end of the elongate body to a distalend of the elongate body; a rotatable tip having spiral wedges at thedistal end of the elongate body and configured to rotate relative to theelongate body; an OCT imaging sensor comprising an optical fiber coupledwith the rotatable tip and configured to rotate therewith, wherein theoptical fiber is configured to wrap around the central lumen within theelongate body as the rotatable tip rotates; and a drive mechanismconfigured to continuously rotate the rotatable tip alternatelyclockwise then counterclockwise.

In another variation, a catheter device for crossing occlusionsincludes: an elongate body; a central lumen extending within theelongate body from a proximal end of the elongate body to a distal endof the elongate body; a rotatable tip at the distal end of the elongatebody and configured to rotate relative to the elongate body; an OCTimaging sensor comprising an optical fiber coupled with the rotatabletip and configured to rotate therewith, wherein the distal end of theelongate body comprises one or more fiduciary markers configured toocclude the OCT imaging sensor as it rotates; and a fixed jog regionproximal to the distal end of the catheter, the fixed jog positioningthe distal end of the catheter at an angle relative to the region of thecatheter proximal to the fixed jog. The fixed jog may form an angle ofbetween about 10 to 45 degrees, so that the distal end is at this anglerelative to the region of the elongate body proximal to the fixed jog.

Also described herein are methods of crossing an occlusion or lesion.For example, a method of crossing an occlusion or lesion may include:advancing an occlusion crossing catheter into a body lumen; rotating arotatable distal tip at a distal end of an elongate body of theocclusion crossing catheter; imaging a region of the body lumensurrounding the catheter using an OCT sensor coupled to the rotatabledistal tip; and passing the rotatable distal tip past an occlusion. Insome variations a guidewire may be placed after passing the occlusion orlesion, so the method may include the step of advancing a guidewire pastthe occlusion by passing the guidewire through a central lumen withinthe elongate body of the occlusion crossing catheter.

In general, the method may include the step of displaying the imagedregion surrounding the body lumen on a screen.

Rotating the rotatable tip may include winding an optical fiber formingthe OCT sensor around the central lumen of the occlusion crossingcatheter. The step of rotating may include alternately rotating therotatable tip clockwise and then counterclockwise.

In some variations, the entire catheter may also be rotated to orient itwithin the body lumen. For example, the catheter body may be rotated toorient a fixed jog and steer the catheter towards damaged tissue.

Image correction may be used to enhance the imaging and user interface.For example, in some variations the image may be corrected, modified orenhanced prior (or concurrent with) display. For example, in somevariations, the image may be corrected prior to displaying the imagedata to account for lag of the OCT imaging senor relative to thedetector. The image data may be corrected to mask out portions of theimage, including regions of the catheter, noise, and the like. Thus, insome variations the image may be an annular region with the innermost(donut hole) region being shown as blank to represent the catheterdiameter, while the outermost region (edge of the annulus) may be maskedto remove artifact.

In some variations, the image taken with OCT imaging may be aligned withother imaging means, including fluoroscopic imaging. For example, themethod may include the step of orienting image data taken with the OCTsensor to align with a fluoroscopy image.

Also described herein are methods of crossing a chronic total occlusionincluding the steps of: advancing an occlusion crossing catheter into anoccluded body lumen of a patient; rotating a rotatable distal tip of thecatheter relative to an elongate body of the catheter, wherein thedistal tip includes at least one helical blade and an OCT imagingsensor; imaging a region of the body lumen surrounding the catheterusing the OCT sensor on the rotatable tip, wherein the catheter includesat least one marker configured to obstruct imaging form the OCT sensorat least once per rotation of the rotatable tip; and steering thecatheter within the body lumen of the patient based upon the OCT imageof the body lumen and the marker.

In some variations, the catheter comprises a fixed jog near therotatable tip having a fixed orientation relative to the at least onemarker, and wherein steering comprises rotating the elongate body toorient the fixed jog. The steering can include pointing the distal endof the catheter toward unhealthy tissue imaged by the OCT sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective view of one variation of a catheter device.

FIG. 2A shows the distal section of an exemplary catheter device.

FIG. 2B is a diagram of a distal section of an exemplary catheter deviceshowing the alignment of markers thereon.

FIGS. 3A-3B show various side perspective views of the distal end anexemplary catheter device.

FIG. 3C shows the distal end of the device of FIGS. 3A-3B, but with thecollar removed.

FIG. 3D shows the distal end of the device of FIGS. 3A-3C, but with thecollar and outer sheath removed.

FIG. 3E shows an embodiment of the distal end of an exemplary catheterdevice wherein the bushing includes a shoulder.

FIG. 4 shows an optical fiber wrapped around a driveshaft of anexemplary catheter device.

FIGS. 5A-5E show a handle assembly or partial handle assembly for anexemplary catheter device.

FIG. 6 shows an exemplary OCT system.

FIGS. 7A and 7B show screen captures of an exemplary catheter deviceincluding an OCT imaging system.

FIG. 8 shows the orientation of an OCT image relative to a fluoroscopyimage from a catheter device.

FIGS. 9A-9C show screen captures used to aid steering an exemplarycatheter device.

FIG. 10 shows an exemplary diagram used to determine the amount ofcentral masking required for an OCT image of an exemplary catheterdevice.

FIGS. 11A-11C illustrate one variation of an exemplary catheter having arotating distal tip region (housing and wedges extendable from thehousing) with the rotating wedges retracted into a rotating housing(FIG. 11A); with the rotating wedges extending from the rotating housing(FIG. 11B); and with the distal end region deflecting (FIG. 11C).

FIGS. 12A and 12B show isometric views of one variation of a system foroscillating the distal end of a catheter, which may be used as part of acatheter device.

FIG. 13A shows an end perspective view of the oscillation system ofFIGS. 12A and 12B.

FIG. 13B-13D illustrate rotation of the camming mechanism and driveshaftof this system.

FIG. 14A shows cross-sections though a vessel with a catheter located inthe true lumen (e.g., surrounded by both the adventitia and media).

FIG. 14B shows cross-sections through a vessel with a catheter locatedin the false lumen (e.g., between the adventitia and the media).

FIG. 15A shows one variation of an exemplary catheter.

FIG. 15B shows another variation of an exemplary catheter including aninflatable centering feature.

FIG. 16A shows the distal end of one variation of an exemplary catheterhaving an inflatable centering feature.

FIGS. 16B and 16C show enlarged views of the proximal and distal ends ofthe inflatable balloon region of the catheter of FIG. 16A, respectively.

FIG. 17 shows one variation of a handle region of the catheter of FIG.16.

FIG. 18 shows the catheter of FIGS. 16A-17 with the inflatable centeringfeature inflated.

FIG. 19A shows the distal end of the catheter of FIG. 18 fully deflated.

FIGS. 19B and 19C show enlarged views of the proximal and distal ends ofthe deflated balloon of FIG. 18, respectively.

FIG. 20A shows an isometric view of closed/non-activated distalatherectomy device assembly. FIG. 20B shows the device of FIG. 20A inthe active/open configuration.

FIG. 21 illustrates the helical auger geometry of the atherectomy deviceshown in FIGS. 20A and 20B.

FIGS. 22A-22D show a variation of a distal atherectomy system with anauger component.

DETAILED DESCRIPTION

The catheters described herein typically include one or more imagingsensors at the distal end that may be rotated independently of theelongate body of a catheter. An imaging sensor may include an opticalcoherence tomography (OCT) sensor. The rotating distal end may alsoinclude one or more tissue cutting or dissecting surfaces that may aidthe catheter in advancing within occluded regions of a vessel.

Examples of the types of catheters that are described herein in detailinclude: (1) guidewire support/placement catheters; (2)support/placement imaging catheters; (3) occlusion crossing catheters(4) occlusion crossing imaging catheters; (5) atherectomy catheters; and(6) atherectomy imaging catheters.

Two sections are included below. Part I describes catheters, includingocclusion crossing catheters, that may be used as guidewire placementand support catheters. In particular, Part I describes cathetersconfigured for imaging from the inside of a vessel, such as an artery,during operation. Part II describes atherectomy devices and methods ofusing them. The sections and subsections provided herein are forconvenience only; it should be understood that features included in onesection or subsection may be included or excluded from devices describedin any of the other sections and subsections.

Part I: Catheters

Catheters, such as occlusion crossing catheters, including guidewireplacement and/or support catheters (which may be referred to as“occlusion crossing catheters” for convenience) may be used to cross anocclusion or lesion. These catheters may be used to place a guidewirewithin an occluded lumen of a vessel. Any of the catheters describedherein may include a guidewire lumen spanning all or most of the lengthof the device and a rotating and/or oscillating (clockwise and/orcounterclockwise relative to the long axis of the catheter) distal tip,which may include one or more dissecting (e.g., cutting) surfaces. Therotatable distal tip region may be used to position a catheter throughan occluded lumen of a vessel, including for treatment of chronic totalocclusions.

Described herein are catheters that include an imaging sensor at thedistal tip to allow imaging of the vessel structure and morphology as itis being traversed. Imaging may be forward-facing, lateral-facing,adjustable between forward-facing and lateral-facing, and/or rear-facingor angled between the forward and lateral facing. Any appropriateimaging modality may be used, but particularly those using one or moreoptical fibers, such as optical coherent tomography (“OCT”).

The catheters described herein can be dimensioned to fit within vesselsof the body, such as blood vessels. For example, the catheters can beconfigured to be placed within the peripheral blood vessels. Thus, thecatheters can have an outer diameter of less than 0.1 inch, such as lessthan 0.09 inches, such as less than or equal to 0.08 inches.

In one embodiment, a catheter device includes a distal tip that isrotatable and an onboard imaging system for visualizing the vessel asthe device is positioned. In this example, the system includes an OCTimaging system for visualizing the structure and morphology of thevessel walls. The system can see a distance of up to 3 mm, such as up to2 mm, into the depth of the vessel walls.

Referring to FIG. 1, a catheter (which may be used as a guidewirepositioning catheter) 100 includes an elongate flexible shaft 301 and arotatable distal tip 305 having an imaging sensor, such as an OCTsensor, connected thereto. The shaft 301 extends from a handle region303 and terminates in the rotatable distal tip 305. The device 100 inFIG. 1 is not necessarily shown to scale, as the length of the shaft hasbeen reduced to show the other features at a more appropriate scale.

A guidewire 309 can extend through the guidewire catheter device 100,such as through a guidewire lumen in the shaft 301. The guidewire 309may be held resident in the device 100 as it is positioned within apatient or it may be inserted after the distal end of the shaft 301, orat least the distal tip 305, has been positioned within the lumen of thevessel, such as past an occlusion or lesion. The guidewire lumen can behoused inside of a driveshaft (not shown in FIG. 1) configured to rotatethe tip 305. Thus, in some variations the driveshaft is a tubular shaftsuch that the driveshaft may surround the guidewire lumen. In othervariations, the driveshaft is a solid shaft which extends through thelength of the catheter, and runs alongside (e.g., adjacent to) theguidewire lumen.

The system can include an optical fiber (not shown in FIG. 1) that isfixed at one end to the distal tip 305, but is otherwise free to movearound, such as within an internal lumen between a lumen housing theguidewire 309 and an outer casing of the shaft 301. Power and imaginglines 307 (“cabling”) may extend from the handle region 303 to connectthe optical fiber with a power source and a light source for the OCTsystem.

The handle region 303 can house the control mechanism for controllingthe rotation of the distal tip (and OCT reflector/sensor at the end ofthe optical fiber). The control mechanism controls the direction of thedistal tip as well as the number of revolutions before switchingdirection. In some embodiments, the handle region 303 can also controlthe rate of rotation. As discussed further below, the rate of rotation,as well as the number of clockwise and/or counterclockwise rotations,may be optimized to advance the distal end of the device though anotherwise occluded lumen of a vessel while generating a cross sectionalimage of the lumen, i.e., 360 degrees. The rate and number of rotationsmay also be optimized to prevent damage to the optical fiber used forthe OCT imaging which is attached only at the distal end of the devicesuch that the rest of the fiber can extend along the length of the shaft301 can wrap, off-axis, around the internal lumen (e.g., guidewirelumen) of the catheter without breaking.

Referring to FIGS. 2A and 2B, the shaft 301 can include a fixed jog 989,or a J-shaped bend, near or just proximal to the distal tip 305. Thefixed jog 989 can have an angle of 10 to 45 degrees, such as between 20and 30 degrees. In some embodiments, the jog is shapeable by the userprior to placing the catheter in the body lumen, i.e., the user can fixthe jog 989 at the desired angle prior to use. As discussed furtherbelow, the fixed jog 989 can aid in steering the shaft 301 to the pointof interest. The shaft 301 can include an outer sheath 284. The outersheath 284 can include a braided material, such as stainless steel,elgiloy, cobalt-chromium alloys, carbon fiber, or Kevlar. The braidedmaterial can improve the stiffness of the catheter to help navigate thecatheter through vessel. Further, the shaft 301 can include a guidewirelumen 363 (see FIG. 3B) extending within a driveshaft 421 (see FIGS.3A-3D) from the proximal end to the distal end of the catheter. Theguidewire lumen 363 can end in an opening in a distal tip 305 of thedevice. The guidewire lumen 363 can thus be configured to pass aguidewire therethrough. Further, the distal tip 305 can include animaging sensor, such as an OCT sensor 286 configured to capture imageswithin a lumen.

Referring to FIGS. 3A-3D, one variation of the distal end of the shaft301 can have a distal tip 305 that is roughly corkscrew or helicallyshaped. The distal tip 305 can thus include spiral flutes, such as twospiral flutes. In this variation, the distal tip 305 rotates and doesnot extend or retract into a housing, i.e. remains exposed from theshaft 301. The distal tip 305 can be attached to a driveshaft 421 thatrotates within the outer sheath 284 and can be configured to rotate inboth the clockwise and counterclockwise directions. Further, the distaltip 305 can include a substantially smooth, curved outer surface 322that presents an atraumatic tissue-contacting surface when rotated inone direction, i.e., the counterclockwise direction in FIGS. 3A-3D, andthat further presents a sharp, tissue-cutting surface or edge 403 whenrotated in the opposite direction, i.e. the clockwise direction in FIGS.3A-3D.

At least a portion of the tip 305, such as the proximal portion of thetip 305, i.e., the proximal portion of the cutting geometry, can have adiameter that is substantially equal to or greater than the diameter ofthe shaft 301. That is, the cutting edge 403 can be helical such that atthe distal end, the diameter of the cutting geometry is reduced to thesize of the guidewire lumen and gradually increases to the approximateouter diameter of the shaft 301 as it moves proximally. Further, the tip305 can be configured such that it cuts only in the forward directionand not substantially in the lateral direction. That is, the cuttingedge 403 can be substantially forward-facing.

An OCT imaging sensor 286 (including the distal end of the optical fiber411 and the mirror 412) can be fixed to the rotatable distal tip 305 androtate with it. The distal end of the optical fiber 411 can be securedin a notch 344 formed in the rotatable distal tip 305. An epoxy or othersecuring material that has a refractive index appropriately mismatchedwith the end of the optical fiber 411 can hold the end of the opticalfiber 411 in the notch 344, as described in U.S. patent application Ser.No. 12/790,703, Publication No. US-2010-0305452-A1, incorporated byreference above. The imaging sensor 286 can direct the optical beam forOCT imaging from the distal tip 305 of the catheter into the tissue. Inone embodiment, the imaging system is oriented so that the mirror 412directs the optical beam approximately or substantially perpendicular tothe catheter axis. In some variations, this angle is different or isadjustable. For example, the orientation of the mirror 412 may bechanged (including adjusted by the user) to change the direction ofimaging and/or image more distally or proximally. As used here,substantially perpendicular may include plus or minus 10 degrees, plusor minus 5 degrees, or plus or minus 2 degrees, off of the 90 degreeangle that is perpendicular from the elongate axis of the distal tipand/or catheter body.

The sensor 286 can be located close the distal end of the tip 305, suchas just proximal to the cutting edge 403. For example, the sensor 286can be located within 5 mm of the distal end of the tip 305, such asless than 3 mm, such as approximately 2 mm. Advantageously, byminimizing the distance between the sensor 286 and the distal end of thetip 305, the resulting image will be a closer approximation of the exacttissue or material being passed by the distal end. The sensor 286 may bedirected laterally (e.g., to image the sides of the vessel in which thecatheter is traveling), or angled forward or backward. The sensor 286can be located off of the central axis of the shaft 301 and close to theouter diameter of the tip 305, such as within 0.05 inches, e.g. lessthan 0.3 inches, less than 0.02 inches, or less than or substantiallyequal to 0.01 inches of the outer diameter of the tip 305.Advantageously, by having the sensor 286 close to the outer diameter,the depth that the OCT system can see into the tissue will be greater,i.e., the amount of tissue lying within the OCT imaging range isincreased.

As shown in FIGS. 3A-3E, the rotating tip 305 is held in a chassis 405that is fixed relative to the shaft 301, i.e., that does not rotate withthe rotating tip 305. The chassis 405 is any structure within which thedistal tip 305 can rotate and which secures the driveshaft 421 and/orthe distal tip 305 to the end of the shaft 301; it may also be referredto as a housing. The outer sheath 284 can be connected to the chassis405 such that the outer sheath also remains stationary while the distaltip 305 rotates.

The chassis 405 can have one or more “window” regions through which theOCT imaging sensor 286 can view the tissue. For example, as shown inFIGS. 3A and 3B, the chassis 405 can include three window regions 346separated by spines 419 (which may be referred to as posts, struts,dividers, separators, etc.) arranged annularly around the chassis 405.These spines 419 may serve as reference markers as the imaging sensor286 rotates, as discussed below. The spines 419 may be separated fromone another by different distances. For example, one of the windows maybe larger than the other two, or smaller than the other two. Thisasymmetric sizing may provide a visual reference on the display of theOCT imaging. Thus, in one example, there are three spines 419 arrangedsuch that there is a 90° window between the first and second spine, a90° degree window between the second and third spine, and a 180° degreewindow between the first and third spine. The spines 419 can have apredetermined and fixed location relative to the jog 989 in thecatheter. For example, one of the spines 419 can be aligned relative tothe jog 989. In one embodiment, shown in FIG. 2B, the second spine 419is aligned opposite to the jog 989, i.e., such that the catheter pointsaway from the second spine 419 (the inner curved portion of the jog 989is opposite to the second spine 419 and the outer curved portion of thejog 989 is axially aligned with the second spine 419). This alignmentcan be used to help orient the device in a specific direction withrespect to the image and/or vessel, as discussed further below.

As shown in FIGS. 3C-D, the distal tip 305 can include a groove 392 atthe proximal end to engage a bushing 394 (e.g., annular ring). Thebushing 394 can remain fixed with respect to the shaft 301 and mayprovide a lubricious surface to eliminate or reduce friction and fix thelongitudinal position of the distal tip 305. The bushing 394 may be madeof PEEK or other hard lubricous material. In some embodiment, the groove392 may be crimped or clamped to the stationary chassis 405, therebyallowing the rotatable distal tip 305 to have improved stability duringrotation.

Referring to FIG. 3E, in another embodiment, the bushing 394 includes ashoulder 445. The shoulder 445 can extend outward into the space betweenthe distal edge of the chassis 405 and the distal tip 305. The shoulder445 can be made of the same lubricous material as the rest of thebushing 394. The shoulder 445 prevents the distal edge of the chassis405 from rubbing against the tip 305 and further reduces the friction ofthe system.

As shown in FIG. 3A, the chassis 405 may engage the groove 392 of thedistal tip 305 directly, such as by one or more tabs 407 or locks thatcan be pushed in when the distal tip 905 is held within the chassis 405to lock the bushing ring 394 and distal tip 305 in position. The chassis405 or distal tip 305 can be made from a lubricious material.

Referring to FIGS. 3A-B, the chassis 405 can include one or moreopenings or ports 422 out of which a clearing fluid, such as saline orwater, may be driven to help clear the pathway for imaging the walls ofthe vessel lumen as the device is operated. Blood, including red bloodcells and other blood components, may degrade the ability of the OCTimaging system from imaging other tissues because OCT may not readily“see” through blood. Thus, the catheter may be configured to clear theblood from the region of interest, i.e., the region where the opticalbeam is emitted from the catheter for OCT imaging. The ports 422 canthus be configured to emit a clearing fluid from the catheter to clearblood from the imaging sensor. Thus, in this variation the port 422 islocated directly adjacent to the imaging sensor and emits fluid to clearblood from the region where the optical beam is being emitted. The ports422 can be less than 2 mm from the imaging sensor, such as less than 1.5mm. Advantageously, by having the ports 422 close to the imaging sensor,the pressure and amount of clearing fluid required to clear the bloodfrom the region of interest can be low. For example, less than 1 ml,such as less than 0.5 ml, e.g., less than 0.2 ml of clearing fluid canbe required to clear the blood from the region of interest. Thus, therequired pressure may be nominal and the flow of saline or otherclearing fluid may be minimal and still effectively clear blood from theimaging space, greatly improving the resolution of the vessel walls andincreasing the depth of penetration. Further, using small amounts ofclearing fluid can advantageously avoid problems associated with havingtoo much fluid in a small space, such as separation of tissue (e.g.,dissection).

The shaft 301 can be configured such that the clearing fluid enters atthe proximal end of the catheter and is transported to the distal end byflowing in a space 472 between the outer sheath 284 and the driveshaft421. The clearing fluid may be pressurized from the proximal end (e.g.,using a syringe, etc.) so that it is pushed out of the opening 422 toclear blood from the OCT pathway.

Referring to FIG. 4, the OCT portion of the catheter device 100 may bereferred to as an off-axis imaging system because the management of theOCT optical fiber 411 is arranged asymmetrically, off-axis withreference to the long axis of the catheter. The fiber 411 can beconfigured to extend freely within the shaft 301 in the space 472between the driveshaft 421 and the outer sheath 284 except where it isattached at the distal end of the device, e.g., at the rotatable distaltip 305. Accordingly, as shown in FIG. 4, when the driveshaft 421 isrotated to rotate the distal tip 305, the fiber 411 can wrap around thedriveshaft 421. This arrangement can advantageously enhance theflexibility, i.e., allow for movement of the catheter without fracturingthe optical fiber 411.

Because the optical fiber 411 winds and unwinds around the driveshaft421 as it is rotated with the distal tip 305, both the rate of rotationand the number of rotations may be controlled to optimize performance,prevent the fiber 411 from binding within the shaft 301, and prevent thefiber 411 from snapping due to excessive twisting or rotation. Forexample, the distal tip 305 may be configured to alternate its rotationfrom clockwise to counter clockwise. Thus, the driveshaft 421 can beconfigured to rotate (with the distal tip 305) clockwise for a fixednumber of rotations and to rotate counterclockwise for the same numberof rotation before switching back to clockwise rotations and repeatingthe process. The number of rotations in the clockwise direction can besubstantially equivalent to the number of counter clockwise rotations inorder to relieve any residual twisting. Advantageously, by having asubstantially equivalent number of rotations in the clockwise andcounterclockwise directions, accumulation of fiber twisting can beavoided, thereby avoiding snapping of the fiber due to such accumulatedtwisting. In general, the device is configured to rotate the distal tipn rotations clockwise and n rotations counterclockwise, switchingbetween clockwise and counterclockwise rotational direction after each nrotations. The number of rotations n can be any number, includingfractional, typically between 1 and 100; preferably it is between 1 and10, depending on the length of the catheter and the amount of stress thefiber can withstand. For example, the device may be configured to rotateapproximately 6, 8.5, 10, 12.7, 15, etc. times clockwise, thencounterclockwise the same number of rotations. Thus, the device isconfigured so that it doesn't continuously spin clockwise orcounterclockwise, but has a limited number of rotations in eitherdirection (e.g., less than 25 rotations, such as 10 rotations), afterwhich it automatically switches to rotate the other direction. Thetransition between clockwise and counterclockwise rotation may beperformed automatically, which is described in more detail withreference to FIGS. 5A-5E, below.

The rotation may be driven by a motor or other driver (e.g., within thehandle) or it may be manual. Preferably, the rotation is automatic, andis driven at a constant speed that is typically between about 1 and 300revolutions per minute (rpm); for example, the rotation rate may beabout 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, etc. In somevariations, the distal tip is rotated between about 1 and about 100 rpm,e.g., between about 1 and 80 rpm, such as between about 30 and 60 rpm.The rate and the consistency of rotation may be optimized forpenetration through the occlusion within the vessel, for imagestability, and also to produce relatively streak-free imaging using theOCT. Thus, the rate of rotation may be limited to an upper limit speedthat is held relatively constant. In addition, the rate of rotation maybe sufficiently low (e.g., less than 150 or 100 or 50 rpm) so that thedistal head rotates but does not ‘drill’ through the tissue, includingone or more occlusions. In some embodiments, the user can control therate of rotation, such as by setting the motor to rotate at a particularspeed.

Referring to FIG. 5A-5E, the handle 303 of the device can be configuredto control rotation and advancement of the shaft 301. The handle 303 caninclude a switch 562 configured to turn the system on or off (i.e. tostart the rotation of the distal tip and/or the imaging system). Thehandle can be covered by a housing 501 which may be configured toconform to a hand or may be configured to lock into a holder (e.g., forconnection to a positioning arm, a bed or gurney, etc.). Within thehandle 303, a drive system, including a motor 503 and drive gears 515,516, 517, may drive the driveshaft 421 to rotate the distal tip 305 ofthe device and/or the OCT imaging system relative to the shaft 301. Insome variations, the drive system is controlled or regulated by atoggling/directional control subsystem for switching the direction ofrotation of the driveshaft between the clockwise and counterclockwisedirection for a predetermined number of rotations (e.g., 10).

In FIGS. 5A-5E, a mechanical directional control can be configured toswitch the direction of rotation between clockwise and counterclockwisewhen the predetermined number of rotations have been completed. In thisexample, the directional control includes a threaded track (or screw)511 which rotates to drive a nut 513 in linear motion; rotation of thethreaded track by the motor 503 results in linear motion of the nutalong the rotating (but longitudinally fixed) threaded track 511. As themotor 503 powers the driveshaft 421 in a first rotational direction(e.g., clockwise), the nut 513 moves linearly in a first lineardirection (e.g., forward) until it hits one arm of a U-shaped toggleswitch 516, driving the U-shaped toggle switch in the first lineardirection and flipping a switch 523 (visible in FIG. 5D) to change thedirection of the motor 503 to a second rotational direction (e.g.,counterclockwise), and causing the nut to move linearly in a secondlinear direction (e.g., backward) until it hits the opposite side of theU-shape toggle switch 516, triggering the switch to again change thedirection of rotation back to the first rotational direction (e.g.,clockwise). This process may be repeated continuously as the motor isrotated. The motor 503 may be configured to rotate the driveshaft 421 ineither direction at a constant speed. The system may also includeadditional elements (e.g., signal conditioners, electrical controlelements, etc.) to regulate the motor as it switches direction.

The number of threads and/or length of the threaded track (screw) 511may determine the number of rotations that are made by the systembetween changes in rotational direction. For example, the number ofrotations may be adjusted by changing the width of the U-shaped toggle514 (e.g., the spacing between the arms). Lengthening the arms (orincreasing the pitch of the screw) would increase the number ofrotational turns between changes in direction (n). The toggle maytherefore slide from side-to-side in order to switch the direction ofthe motor. The length of the nut 513 can also determine the number ofrotations that are made by the system between changes in rotationaldirection, i.e., the longer the nut, the fewer the number of rotationsbefore switching direction.

In some variations, the motor 503 is rotated in a constant direction,and the switch between clockwise and counterclockwise is achieved byswitching between gearing systems, engaging and disengaging anadditional gear, or using gears that mechanically change the directionthat the driveshaft is driven.

In the exemplary device shown in FIGS. 5A to 5E, the drive systemincludes the motor and three gears that engage each other to drive thedriveshaft in rotation. For example, the motor 503 rotates a first gear517, which is engaged with a second gear 516 (shown in this example as a1:1 gearing, although any other gear ratio may be used, as appropriate).A third gear 515 engages with the second gear 516. The third gear maydrive or regulate an encoder 507 for encoding the rotational motion.This encoded information may in turn be used by the drive system,providing feedback to the drive system, or may be provided to theimaging system.

Referring to FIG. 5E, the cabling 307 can include both a fluid flushline 552 configured to be attached to a fluid source and an opticalfiber 411 configured to be connected to the OCT system. The flush line552 and the fiber 411 can both run through the handle 303. The fiber 411and the flush line 552 can be bonded at a bonding point 566 in thehandle 303, creating a seal to prevent fluid from leaking into thehandle. The flush line 552 can end at the bonding point 566, allowingthe fluid to exit the flush line and continue down the shaft 301 in thespace 572 between the outer sheath 284 and the driveshaft 421. Further,the fiber 411 can extend through the bonding point 566 and wrap aroundthe driveshaft 421 in the space 572. As shown, because the fiber 411 isconfigured to wrap around the guidewire lumen, a separate fibermanagement system is not necessary. In some embodiments, a protectivecoating 564 can surround the optical fiber until distal of the bondingpoint 566.

Referring to FIG. 6, the fiber 411 can be connected at the proximal endto a common-path OCT system 600. The common-path OCT system 600 includesa light source 102, such as a swept frequency laser. In an alternativearrangement, the light source could be a broadband light source such asa super-luminescent diode (to conduct Time Domain OCT or Spectral DomainOCT using an optical spectrometer). The optical fiber 411 transfersradiation from the light source 102 to the target 114. The optical fiber411 is in optical contact with an interface medium 106, i.e. the lightexiting the optical fiber and entering the interface medium sees onlyone interface. In some embodiments, as shown in FIG. 6, the end of theoptical fiber is embedded in the interface medium 106. The interfacemedium 106 can be, for example, a glue or epoxy. In the common-path OCTsystem 600, the index of refraction of the interface medium 106 isdifferent than the index of refraction of the core of the optical fiber411. This creates a Fresnel reflection, in which part of the light exitsthe core, and part of the light is reflected back. Some of the lightbeam that exits the optical fiber 411 will encounter the target 114 andbe reflected or scattered by the target 114. Some of this reflected orscattered light will, in turn, reenter the tip of the optical fiber 411and travel back down the fiber 411 in the opposite direction. A Faradayisolation device 112, such as a Faraday Effect optical circulator, canbe used to separate the paths of the outgoing light source signal andthe target and reference signals returning from the distal end of thefiber. The reflected or scattered target light and the Fresnel-reflectedreference light from the fiber face can travel back to a detector 110located at the proximal end of the optical fiber 411.

Because the reflected or scattered target light in the OCT system 600travels a longer distance than the Fresnel reflected reference light,the reflected or scattered target light can be displaced by frequency,phase and or time with respect to the reference beam. For example, ifswept-source radiation is used, then the light from the target will bedisplaced in frequency. The difference in displacement in phase, time orfrequency between the reflected or scattered target light and thereference light can be used to derive the path length difference betweenthe end of the optical fiber tip and the light reflecting or lightscattering region of the target. In the case of swept source OCT, thedisplacement is encoded as a beat frequency heterodyned on the carrierreference beam.

The light source 102 can operate at a wavelength within the biologicalwindow where both hemoglobin and water do not strongly absorb the light,i.e. between 800 nm and 1.4 μm. For example, the light source 102 canoperate at a center wavelength of between about 1300 nm and 1400 nm,such as about 1310 nm to 1340 nm. The optical fiber 411 can be a singlemode optical fiber for the ranges of wavelengths provided by the lightsource 102.

FIGS. 7A and 7B are exemplary screen captures of an imaging output fromthe system described herein. In FIGS. 7A and 7B, the displayed image 800is divided into three components. On the right is a fluoroscopic image810 showing the distal end 805 of the catheter within a vessel 814.Contrast has been inserted into the vessel 814 to show the extent of thevessel 814 and any occluded regions.

On the left is an OCT image 820. To obtain the OCT image 820, the distaltip of the catheter rotates at approximately 30 rpm, and the OCT systemprovides a continuous set of images as the catheter rotates within thevessel. The images are combined into a continuously updated OCT image820 that corresponds to the inside of the lumen in which the catheter isinserted. That is, the OCT image 820 is an image trace of the interiorof the vessel just proximal to the distal tip as it rotates. The line822 (extending to almost 12 o'clock in the figure) indicates the currentdirection of the OCT laser beam as it is rotating. The circle 824 in themiddle of the image 820 represents the diameter of the catheter, andthus the area surrounding the circle 824 indicates the vessel. The OCTimaging can extend more than 1 mm from the imaging sensor, such asapproximately 2 mm or approximately 3 mm and thus will extend into thewalls of the vessel (particularly in the closer region of the vessel) sothat the different layers 826 of the vessel may be imaged. In thisfigure, the three striped rays 744 (extending at approximately 2o'clock, between 7 and 8 o'clock, and approximately 11 o'clock) indicatethe location of the three spines of the catheter and thus may act asdirectional markers, indicating the orientation of the distal end of thecatheter within the body. As described in more detail below, the usermay also be able to determine relative orientation of the OCT image(relative to the patient's body orientation) using these striped rays744.

On the bottom left of the image 800 is a waterfall view 830 of the OCTimage as it circles the radius of the body. This waterfall image 830 maybe particularly useful in some applications of the system, for example,indicating the relative longitudinal position of a feature (e.g.,layered structures, occlusions, branching region, etc.) as the device ismoved longitudinally within the vessel. The waterfall view 830 typicallyincludes a time axis (the x-axis) while the y-axis shows the image fromthe OCT sensor. In addition, the waterfall view 830 may provide anindication of when the catheter has crossed an occlusion. For example,the waterfall view 830 may show the patient's heartbeat when the wallsof the vessel move relative to the heartbeat. In these cases, thewaterfall view 830 may show the walls of the vessel moving with theheartbeat. In contrast, when the distal tip is within an occlusion thewall of the vessel, the waterfall view will not show movement of thewalls since the occlusion material typically prevents the movement ofthe walls due to the heartbeat, while in healthy vessels the heartbeatis apparent. Thus it may be possible to determine when the catheter hascrossed the occlusion based on the waterfall view 830. In somevariations, this effect may be automated to provide an indication ofwhen the device is within or has crossed an occlusion. In general,crossing the boundary of a total occlusion is not well defined and mayresult in inadvertently dissecting the vessel. When the catheter iswithin the true lumen, the vessel wall may move; if the catheter tip isnot in the true lumen all or part of the vessel wall will not move.Thus, this movement of the wall during heartbeat may reflect theposition within the true versus false lumen.

FIG. 7B shows another screen capture from the same procedure shown inFIG. 7A. As shown in the fluoroscopy image 810, the distal tip 305 isfurther within the vessel 814 than in FIG. 7B. In this example, the OCTimage 820 shows a branch 818 of the vessel extending from the vessel inthe 2 o'clock position.

The generated fluoroscopy images and OCT images can be oriented relativeto one another, e.g., so that what the user sees on the right side ofthe OCT image is consistent with what the user sees on the right side ofthe fluoroscopy image. Referring to FIG. 8, the shaft 301 can include afluoroscopy marker 702 (also shown in FIG. 2B and FIG. 4) that providesvarying contrast in a fluoroscopy image depending on its radialorientation. The marker may be a radiopaque band with one or moreasymmetric features such as a “C”, “T”, or dog bone shape that can beused to radially orient the shaft because the fluoroscopic image of themarker will change depending on its orientation. The fluoroscopy marker702 can have a fixed location relative to the spines 419 and/or the jog989. For example, as shown in FIG. 2B, the fluoroscopy marker 702 can bealigned opposite to the jog 989 and/or axially aligned with the secondspine 419 described above. The fluoroscopy marker 702 can be used toalign a fluoroscopy image 710 with an OCT image 720 during use of thecatheter.

As shown in FIG. 8, to align the fluoroscopy image 710 with the OCTimage 720, the shaft 301 can be rotated slightly such that the marker702 is aligned to a particular side of the screen, such as at the 9o'clock position. The up/down position of the catheter (i.e. whether thecatheter is pointed down, as shown in FIG. 7, or pointed up) can also bedetermined. After the rotational position and the up/down position ofthe catheter have been determined using the fluoroscopy image 710, theOCT image can then be oriented such that striped ray 744 from the middlemarker (the second spine 419 described above) of the shaft 301 is alsoat the 9 o'clock position in the OCT image 720. Such positioning can betermed “fluorosyncing.” Fluorosyncing can be performed using manualinput from the user, such as information regarding the up/down positionand the rotational position, or can be performed automatically. Toorient the OCT image 720 using this information, the software may drawthe OCT image 720 either in a clockwise or counterclockwise direction(depending on the up/down orientation of the catheter in the fluoroscopyimage 710) and will rotate the image 90°, 180°, or 270° (depending onthe rotational position of the catheter in the fluoroscopy image 710).

Once the fluorosync has been completed, the absolute and relativeposition and orientation of the catheter within the patient's body maybe determined. The markers on the chassis/imaging system (visible in theOCT system) may therefore provide sufficient orientation markers suchthat the fluoroscopic imaging may be reduced.

The displayed images can be used, in combination with steeringmechanisms such as the OCT markers, the fluoroscopy marker, and thefixed jog of the device, to steer the catheter and rotatable tip to thedesired location. Referring to FIG. 9A, the OCT image 920 shows healthytissue 956 in the form of a layered structure and non-healthy tissue 958in the form of a nonlayered structure. The cat ears 962 in the imageshow a region between the healthy and unhealthy tissue caused by aslight expansion of the vessel around the catheter at that location.Accordingly, during a CTO procedure, one goal may be to steer thecatheter towards the unhealthy tissue. Because the middle spine 419 isaligned opposite to the jog 989 (as shown in FIG. 2B), the ray 744corresponding to the middle spine 419 can be oriented opposite to thenon-healthy tissue 958 to steer the catheter in the correct direction.FIG. 9B shows the catheter deflected toward the layered, healthy tissue.FIG. 9C shows the catheter rotated such that it is deflected toward theunhealthy, non-layered structure. Thus, the system may be configured toallow the orientation of the catheter to be rotated into the correctposition using the fixed directional markers from the chassis that arevisualized by the OCT. In some variations, the distal end of the devicemay be steerable and may be steered while still rotating the distal endof the device.

Additional steering members may also be included, such as a selectivestiffening member, which may be withdrawn/inserted to help steer thedevice, and/or one or more tendon members to bend/extend the device forsteering.

Image correction can be performed on the resulting OCT images in orderto mask out unwanted or unnecessary portions of the image. For example,referring to FIG. 10, the fiber 411 can be configured such that it endswithin the shaft 301. As a result, the fiber 411 will image the distancec1 between the fiber 411 distal end and the mirror 412 as well as theaxial distance c2 between the mirror 412 and the outer diameter of theshaft 301. The resulting image would therefore include portions thatcorrespond to the interior of the shaft. Accordingly, image processingcan be performed such that distance c1, c2, or c1+c2 is masked out inthe displayed image. In the case where c1 and c2 are masked out, onlythe area c3 would show up on the image (where the total imaging distanceor capability of the fiber is equal to c1+c2+c3). For example, up to 100pixels can be masked out, such as between 20 and 60 pixels, for exampleapproximately 40 pixels.

Additional image processing is possible. For example, the image can becorrected to account for lag of the optical fiber in the amount ofrotation at the handle vs. at the distal end of the catheter. Images forlag correction can be captured automatically. Further, images can beexported and stored, for example in a movie format. The images canoptionally viewed in adjustable grayscale. Further, the speed of thewaterfall view can be adjusted. In some variations, and offset or“ghost” image may be overlaid atop the OCT to indicate the differencebetween the predicted and actual rotational orientation of the catheter.

The catheter variation described immediately above provides an internalmotor for rotating the distal tip. In some variations, a manuallyrotatable device may be used with an adjunctive device providing amotorized movement of the distal tip. In this variation, the handleportion of the device may set and be secured within a housing thatincludes a motor and gearing to automatically rotate the distal tip at apredetermined or adjustable speed. Thus, this motorized accessory devicemay adapt an otherwise manual device to automatically rotate.

Other variations of catheters are possible that include one or more ofthe features described above.

In some variations, the rotatable distal tip includes a fixed orrotatable housing from which dissection elements may extend or retract.An imaging element, such as an OCT imaging element, may be included inthis embodiment as well. Referring to FIGS. 11A-11C, in some variations,wedges 49 may be extended from a rotatable distal tip 50. In FIG. 11A,the device is shown with the wedges retracted into the rotatable distaltip 50. In FIG. 11B, the wedges 49 have been extended from the housing46. The distal end of the device can be shared and is shown deflectingupwards (steering in one plane) in FIG. 11C while the wedges areextended from the housing.

Both the distal tip and the wedges can be configured to rotate. Thewedges 49 (which may be sharp blades or may be blunt) can be extendedfrom the distal housing and locked in any position (extended, partiallyextended or retracted) and rotated clockwise and/or counterclockwisewhile locked in a retracted, extended or partially extended position.

The wedges may be fully or partially retracted into a distal housing.The extension of the wedge from the distal housing may be limited. Forexample, the wedges may be prevented from extending fully out of thedistal housing, thereby preventing material (such as a plaque or tissue)from getting caught between the wedges and the housing.

The wedges at the distal end may be referred to as a blade or blades,even though they may be substantially blunt. In some variations thewedges are configured so that they are forward-cutting, but notside-cutting. This means that they may include a forward-facing cuttingedge, and the more lateral edges may be blunted or less sharp. In somevariations, the rotating distal tip includes only a single wedge, ratherthan multiple wedges. The wedge (blade) may be helically arranged at thedistal tip.

In one embodiment, the rotating distal end comprises two or more wedgesthat are radially separated around the tip region (e.g., spaced equallyapart radially). It may be advantageous to have three or more wedgesspaced around the tip, which may improve centering of the device, asdescribed herein.

In the examples provided above, the distal tip of the device is rotatedthrough multiple complete rotations (both clockwise andcounterclockwise) to move the distal tip and/or any attached imagingsensor in rotation around the elongate longitudinal axis of the device.In some variations the distal tip of the device (including theatherectomy devices described below) may be rotated through partialrotations. This is illustrated in FIGS. 12A-13D. In this example, adriveshaft rotates continuously in one direction, e.g., clockwise, butthis one-directional rotation is translated at the distal end of thedevice into oscillating motion.

FIG. 12A shows a partially transparent view of one variation of anoscillatory motion system for rotating the distal end portion of acatheter back and forth (clockwise and counterclockwise) though apartial rotation, such as less than 360 degrees, e.g., less than 180degree, etc. In this example, the system is shown connected to anoscillation/rotating element 801 to which the imaging sensor, includinga mirror 811 and the distal end of an optical fiber 813 for theexemplary OCT system, are connected. Thus, oscillation of theoscillation/rotating element 801 moves the OCT sensor to image anangular view of the field of view. The oscillation/rotating element 801may be moveably housed within an outer housing 802 which may remain“fixed” relative to the inner oscillation/rotating element 801. Theouter housing 802 may be connected to the rest of the catheter. In somevariations, this catheter is strictly configured for OCT imaging and isnot configured for atherectomy or for guidewire positioning.

FIG. 12B shows the device of FIG. 12A with the outer housing 802removed. The oscillation/rotating element 801 includes a C-shaped endregion into which a camming member 805 that is attached to therotating/rotatable driveshaft 803 is housed. The camming member 805 inthis example is a cylindrical member to which the driveshaft 803 iseccentrically connected, so that the center of the longitudinal axis ofthe driveshaft 803 is off-axis for the center of the longitudinal axisof the camming member 805. This is illustrated in FIG. 13A, which showsthe camming member 805 and attached driveshaft 803 within the C-shapedcut-out of the oscillation/rotating element 801.

In operation, rotation of the driveshaft will rotate the camming member805 as illustrated in FIGS. 13B-13D, pushing the oscillation/rotatingelement 801 first clockwise, then counterclockwise to subtend an arcwithin the outer housing. This motion thereby allows scanning of the OCTimaging system across this arc. The larger the camming member and/or thegreater offset of the driveshaft and the camming member, the greater thearc traversed by the oscillation/rotating element 801.

As mentioned above, any of the catheters described herein may be used totreat peripheral vascular disease. In particular, the catheters may beused to place one or more guidewires across an occlusion, so that theocclusion may be imaged, removed, and/or displaced. Referring to FIGS.14A and 14B, in some variations, the devices described herein arecentering or self-centering within the lumen of the vessel. The vessel441 (shown in cross-section on the left a transverse section on theright of each figure) includes the media 442 (e.g., tunica media)surrounded by adventitia 443 (e.g., tunica adventitia). Duringoperation, it is desirable that the devices 400 remain centered withinthe “true” lumen 445 (the center) of the vessel 441 as shown in FIG.14A, rather than a “false” lumen 446, i.e., the region between theadventitia 443 and media 442 as shown in FIG. 14B. If the catheterdevice does end up in the sub-intimal plane (e.g., false lumen 446), asillustrated in FIG. 14B, the device may reside between the media 442 onone side and the adventitia 443 on the other. To ensure that the devicesdescribed herein end up in the true lumen 445, the devices may beconfigured for both passive centering (self-centering) and activecentering (including a centering mechanism).

In some configurations, the devices described herein are self-centeringand are thus configured to help maintain the catheter (e.g., the tip ofthe catheter) within the true lumen. When used to treat chronic totalocclusions, the manually or automatically rotatable distal end of thecatheter may guide the catheter in the true lumen, especially when thereaching the distal cap of a lesion. For example, because the diameterof the rotating distal end may be at least equal to the diameter of themore proximal regions of the elongate body of the device, the tip may besufficiently blunt to passive self-center within the lumen of a vessel.However, if the device does end up within the “false lumen”, it can beconfigured to self-center back into the true lumen. That is, the elasticnature of adventitia typically prevents the tip from engaging andtearing the tissue. At the same time, it is easy for the rotating tip toengage with the media if it is presented in the front of the device,which may include the tissue-cutting surface(s). Thus, the rotating tipmay selectively dissect its way through the media and not throughadventitia. Once the device dissects its way through the medial, itreturns to the true lumen.

Although centering (self-centering) of the catheter may result from therotation of the distal end for the dimensions of the devices illustratedherein, one or more additional centering features may also be used tohelp the device to stay in true lumen of the blood vessel. Thus, in somevariations, the catheter may be configured for use with one or morecentering features to help prevent the distal tip from leaving the truelumen. The centering feature may project from the distal tip, thelateral sides of the distal tip, or the lateral sides of the distal endregion, e.g., proximal to the distal tip.

In some variations, the centering feature is a balloon that expands (oris expandable, inflatable, or otherwise extendable from the lateralsides of the distal end region of the device) to keep the distal tipcentered in the lumen. The device may also be deflectable or steerableat the distal tip region, as previously described, and/or may includeone or more sensors (e.g., OCT imaging as described above), to helpdetect when the tip is approaching or has passed into the false lumen orotherwise left the true lumen.

For example, FIG. 15A illustrates one variation of a catheter (asdescribed in patent application U.S. Ser. No. 12/689,748, previouslyincorporated by reference) which may have a rotating distal tip region.FIG. 15B shows a catheter 500, similar to the catheter of FIG. 15A, butincluding a balloon 522 located proximal to the rotating distal tip.Although only this catheter design is shown with the centeringmechanism, it is to be understood that the centering mechanism couldapply to any of the catheter configurations described herein. In somevariations, the balloon may cover or extend over the rotating distal tipregion. In this example, the distal end region (proximal to the distaltip 101 that rotates) may include a balloon 522 that is collapsed aroundthe outer diameter of the catheter shaft 103, but may be inflated andexpanded against the walls of the vessel. In addition to centering thedistal end of the catheter shaft 103, expanding the balloon 522 may alsoexpand the opening or passageway through the vessel. This may, in turn,improve treatment outcomes with the device, perhaps by loosening orpreparing the atheroma (or other occlusion) for removal or displacement.In FIG. 15B, the proximal region of the catheter shaft 103 includes aport 524, for example a y-type connector, for inflation fluid, that maybe use to inflate and deflate the balloon 522. Any appropriate inflationfluid may be used, including water, saline, lubricant, dye, or somecombination of these.

In this example, the catheter 500 is fabricated similarly to thecatheters described previously, i.e., to include an inner lumen forpassage of a guidewire, surrounded by a driveshaft forrotating/oscillating the distal tip, and again surrounded by an outerdiameter jacket (e.g., of a flexible, braided stainless steel, polymer,etc.). Referring to FIGS. 16A-16C, prior to lamination of the outerjacket 537, on the outer catheter, an additional tube 533 to form theinflation lumen 535 (e.g., a 0.011″ ID polyimide tube) is fused alongthe side of the outer catheter during lamination. A mandrel 539 (e.g., a0.009″ stainless steel mandrel) may be inserted during assemblyprocessing to insure patency of the inflation lumen, and removed uponcompletion.

A balloon 522 (e.g., formed by nylon extrusion) may be attached near thedistal end (e.g., proximal to the distal end of the catheter 500, asillustrated in FIG. 15B, and also FIGS. 16A-16C. The balloon 522 canhave a nominal dimension of approximately 10 cm in length and a diameterof 5 mm (expanded). The balloon 522 has two rounded shoulder regions,one at the proximal end and one at the distal end; in some variationsone or both ends may be tapered. In FIG. 16A-C, the inflation lumen endsbetween the proximal and distal end of the balloon, e.g., near thecenter of the balloon, and terminates in a skived opening to allowentry/exit of inflation material. In some variations, the balloon 522has a slightly smaller diameter at the proximal end compared to thedistal end to compensate for the missing inflation lumen at the distalend; thus, the overall outer diameter of the catheter 522 may be remainrelatively constant.

The balloon 522 may be fused to the outer portion of the distal end ofthe catheter, as shown in FIGS. 16A-C. For example, a short length ofPEBAX tubing may be added to the shaft at the locations where the distaland proximal ends (legs) of the balloon will be located. These PEBAXlengths may be used to ensure that enough material seals and fuses theballoon to the outer shaft. FIGS. 16B and C show the fused proximal(“rear leg”) and distal (“front leg”) regions of the balloon. Prior tofusing the balloon 522 to the shaft, the inflation lumen 535 (polyimidetube) is skived at the distal end to correspond to a location of thedistal inflation/deflation hole approximately midway along the length ofthe balloon 522. The balloon 522 may be folded, sealed and/or heat set(e.g., to maintain the small delivery diameter, etc.). For example, theballoon 522 may be pleated, folded and heat set.

FIG. 17 shows one variation of the handle region 725 of a catheter 500including a balloon-type centering feature. In this example, theproximal end of the device includes a Y-arm with an inflation/deflationport or lumen 535, and sealed in position, to prevent leakage. In somevariations, a separate inflation lumen is not included, but all or aportion of the region between the outer sleeve and the inner catheter(e.g., the central or offset guidewire lumen) is used as the inflationlumen connecting the inflation port to the balloon.

The dimensions of the entire catheter, including the balloon and distalend region may be adjusted. In one example, the dimensions (un-inflated)are approximately: proximal shaft has a diameter between about 0.074inches and 0.084 inches; the mid-shaft region has a diameter betweenabout 0.074 inches and 0.079 inches; the proximal balloon leg has adiameter between about 0.085 inches and 0.094 inches; the distal balloonleg has a diameter between about 0.079 inches and 0.085 inches; and themid region of the balloon over the inflation lumen has a diameterbetween about 0.077 inches and 0.085 inches. The double wall thicknessof the balloon is approximately 0.0045 inches, and the catheter has alength from the distal end of the proximal assembly to the distal tip ofthe device of 111 cm, while the length from the distal end of the Y-armto the distal tip of the device is approximately 91 cm. When inflated to6 atm pressure, the balloon has a proximal diameter of about 0.218inches, a mid-diameter of approximately 0.211 inches, and a distaldiameter of approximately 0.210 inches (at 10 atm in this example, theproximal diameter was about 0.222 inches, the mid-diameter wasapproximately 0.216 inches, and the distal diameter was approximately0.215 inches.

FIG. 18 shows one example of the catheter 500 with a balloon 522inflated to approximately 6 atm with water. Deflation may be achievedusing the inflation/deflation lumen 535. In one example, completedeflation took approximately 3 min. However, this may be faster or maybe performed slower by adjusting the annular size of the inflation lumenor the viscosity of the inflation fluid. The balloon 522 was deflateduntil little or no residual inflation fluid was present in the balloon.

FIGS. 19A-C illustrate the balloon 522 of FIG. 18 after deflation andremoval of the inflation fluid. In this example the balloon 522 has notbeen folded and/or pleated (or heat-set into this folded/pleatedconfiguration), so the balloon collapses as shown. In some variations,the outer diameter of the catheter may be kept small in the deflatedconfiguration.

Other variations of centering feature may be used as well, not limitedto the annular/toroidal balloon described above. For example, in somevariations one or more arms may extend from the outer shaft of thedevice and apply lateral force against the walls of the vessel to centerit within the lumen. Alternatively, a coil located near the distal endand coiling around the distal end region may be expanded to extend loopsoutward and center the device. Any appropriate material, including shapememory materials (e.g., nickel titanium) may be used, and the centeringfeature may be configured to be atraumatic when contacting the vessellumen (e.g., having rounded or flat, large-diameter tissue-contactingsurfaces, etc.).

The guidewire positioning devices described herein may be configured assingle-use, over-the-wire, devices. For example, the device may becompatible other guidewires of standard sizes used in minimally invasiveprocedures. The outer diameter of the elongate device (including thedistal end region) may fit within a 7F sheath. The devices may be usedwith any appropriate guidewire, including steerable guidewires. Forexample, the guidewire may be a 0.035″ guidewire. These devices maygenerally be described as “steering” a guidewire, although they may beused with a guidewire within the catheter, or the guidewire may bepositioned within the device after the catheter has been positioned.

In general, these devices may provide support and guidance forpositioning a guidewire across an occlusion. As described herein, thedevices may support probing and exchange of an assortment of guidewires,by traversing an occlusion in a vessel. Typically, the catheters areinserted ahead of the guidewire (or with the guidewire retracted withinthe catheter) to provide a safe pathway thorough the occluded vessel,and thereby reduce or eliminate unnecessary damage to the vessel. Inaddition, the devices described herein may be used to deliver contrast.The internal lumen which may be used by the guidewire and/or the outerlumen may also be used for local dye or fluoroscopic contrast injectionswithout removing the device from the vessel.

In operation, the rotating/oscillating distal tip allows the device tobe passed through an occlusion such as a plaque occluding a blood vessel(or artery) without requiring removal of the plaque. Thus, the devicemay be used to bluntly form a pathway through a plaque using theretractable/extendable rotating wedges at the distal tip, or simplyusing the rotating distal tip alone. The cutting edges at the distal tipmay also allow for helical and blunt micro-dissection. It is importantto note that the catheter may be used without substantially dissectingor cutting the tissue, and that the distal tip is not necessarilyintended (and may not) remove tissue, but merely form a passage throughan occluded vessel. Once in position, the guidewire may be used toinsert other devices, including atherectomy catheters.

In some variations, the cutting edges at the distal tip are sharp (e.g.,cutting or knife-edged), while in other variations the cutting edges aresubstantially blunt. The cutting edges are typically curved around oralong the longitudinal axis of the distal tip. For example, the cuttingedge may extend helically around the distal tip end of the device.

In some variations, the catheters described herein may be used (e.g.,inserted) in to the body in a 7F guide sheath for placement into thebody. In general, the elongate catheter is flexible, and the outersurface(s) may be coated so that the catheter can be readily insertedinto a lumen of a sheath, catheter, or directly into a body lumen. Theelongate outer sheath is typically tubular, and may be coated (either orboth inner and outer diameter surfaces) with a protective cover. Theelongate outer sheath may be referred to as a shaft (e.g., cathetershaft), and may be coated with a lubricious material or may be formed ofa smooth and/or lubricious material.

In some variations, the distal tip of the catheter is retractable intoan expanded approximately toroidal-shaped distal balloon that isexpanded proximal to the distal tip. This variation may allowre-centering or re-orientation of the catheter.

As noted above, the distal end of the catheters described herein may besteerable. The distal end region may be steerable in any appropriatemanner. In particular, the distal end region may be steerable bydefecting in one direction (e.g., ‘down’) or in more than one direction(e.g., down/up, right/left, etc.). The degree of deflection may also becontrolled. In some variations, the tip may be deflected a maximum of 10degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 45 degrees, 60degrees, 90 degrees, or any angle there between. In some variations thedistal end region of the device is pre-biased to be straight. Thereforethe straight configuration of the distal tip may be restored once thedeflection (controlled at the proximal end) is restored to the straightconfiguration. In addition to be deflectable, in some variations thedistal end of the device is flexible. The end region may include the tip(e.g., the rotating tip) or it may include the region immediatelyproximal to the tip. In general the “tip region” may refer to therotatable tip region at the distal end. The deflection may be performedby any appropriate method, including a pullwire coupled to a hingeddistal region, a prebiased curve which can be released (e.g., by apullwire, etc.), etc.

Deflection or steering of the distal end may help with re-entry of thedevice. For example, the deflectable/steerable distal end region (whichmay be referred to as the “steerable tip”) may allow the catheter tore-enter the true lumen of the vessel if it becomes subintimal (e.g., ifit extends into the fascia or region around the vessel).

In some variations, as described above, the distal region of thecatheter is prebent, e.g., includes a jog. In other variations, thecatheter includes a bendable distal end. Steering these catheters may beaided by visualization and may include rotating the length of thecatheter body, which may be guided by imaging. Rotation or turning ofthe catheter body may be used to orient the distal tip region because ofthe bend in the catheter, in both fixed bend and bendable catheters.

In general, the proximal handle may act as an interface with theoperator, and may include one or more controls. The handle region mayalso include connections to power (e.g., in automaticrotating/oscillating variations), imaging (e.g., connection to imagingsource and processing), or the like.

The devices described herein may be any appropriate length, butrelatively short length catheters may be particularly useful. Forexample, the device may be approximately 100 cm, allowing the device toreach any occlusion down to the popliteal and ease physician handlingoutside the body. In other variations, the device is between about 50and 150 cm, between about 70 and 120 cm, etc.

As mentioned, the distal tip may be driven by an elongate driveshaft (or“torque shaft”) that extends the length of the device. This driveshaftis typically robust, allowing increased torque precision andmanipulation during the operation. For example, the torque shaft may bemade of a braided stainless steel material having a hollow lumen(forming or surrounding a central, e.g., guidewire, lumen of thedevice). Rotation of the driveshaft typically drives the distal tiprotation. The driveshaft is typically flexible and connects to therotational control at the proximal end (e.g., handle). The distal tip,including the wedges and housing, may rotate both clockwise andcounterclockwise.

The handle region at the proximal end of the device may also be adaptedfor handheld use. In particular, the controls at the handle region maybe adapted so that the device may be manipulated by a single hand. Insome variations the handle region may also include one or moreindicators or displays for displaying the status of the distal end ofthe device. For example, the handle may include an indicator indicatingthe extent to which the wedges are extended from the distal tip. Theindicator may be a dial, slider, or the like. The indicator may bemarked or unmarked. The proximal handle may be otherwise configured tobe handheld. For example, the controls may be clustered or located atone end of the handle with a gripper region at the other end. Forexample, the controls may be clustered at the proximal portion of thehandle (allowing the distal portion of the handle to be gripped in thepalm of the hand, and manipulate d by the thumb and forefinger of theright.

In general, the elongate outer sheath of the catheter is flexible, andmay be coated so that it can be readily inserted into a lumen of asheath, catheter, or directly into a body lumen. For example, theelongate outer sheath of the catheter may be formed of a braidedstainless steel, a polymer, or the like. The elongate outer sheath istypically tubular, and may be coated (either or both inner and outerdiameter) with a protective cover. The elongate outer sheath may bereferred to as a shaft (e.g., catheter shaft), and may be coated with alubricious material or may be formed of a smooth and/or lubriciousmaterial.

The dimensions of the devices described herein (including in thefigures) may be varied while staying within the scope of the inventionas generally described. Unless otherwise indicated, these dimensions areintended as merely illustrative and not limiting.

As mentioned briefly above, various aspects of the devices describedherein provide substantially benefits compared to other device which maybe used in occluded vessels, including rotating devices. For example,the forward cutting blades may prevent cutting on the sides/walls of thelumen. This configuration may also help with self-centering, asmentioned. In addition, the device may be configured so that thediameter of the blade (e.g., wedge) region is the same as the diameterof the rest of the catheter. Thus, the diameter of the distal end havingthe rotatable wedge is maximized so that the blades are the samecrossing profile as the rest of the catheter, which may allow foroptimal engagement within the occlusion in the vessel.

In some variations, the guidewire lumen described herein is not central,but is offset along all or a portion of the length of the device. Thelumen (or a separate lumen) may also be used to pass a material such asa contrast dye, saline, an imaging device, etc. An outer lumen maysurround the inner (guidewire) lumen, and may enclose this space to forma separate lumen in which one or more additional lumens (e.g., inflationlumen in variations including a balloon or expandable feature) may beincluded; a driveshaft for rotating or controlling rotation of thedistal tip may also be included.

As described above, the proximal end of the device typically includes ahandle region that may be used to control the distal end. For example,the device may include a rotation control, a wedge articulation controland/or a steering control. In some variations these controls may becombined into one or more controls or these functions may be distributedor divided between different controls. Any appropriate control may beused, including slides, knobs, dials, buttons, levers, switches, etc. Insome variations the controls may be automated or computer-controlled. Insome variations a driver (e.g., motor, mechanical driver, etc.) may beused to drive the controls. For example, rotation of the distal tipregion may be driven by a motor, and may be geared or otherwisecontrolled. The rotation may be manually or automatically controlled.

Part II: Atherectomy Catheters

One variation of an atherectomy catheter (which may be used afterplacement of a guidewire as described above) is illustrated in FIGS.20A-22D and described below. In general, an atherectomy catheter mayaccess the vasculature using conventional catheterization techniquesemploying sheath and/or guiding catheter access and tracking over apositioned guidewire. The device may track through the vasculature tothe target lesion. A fiber (e.g., a Single Mode fiber) can be positionedat or near the distal assembly of the device and to enable imaging(e.g., OCT imaging) to be used for lesion assessment and treatmentplanning. For example, the device may be rotationally oriented towardthe diseased sector of the artery, and activated using proximalphysician controls to preferentially expose the cutting edge to thediseased tissue. In the variation described herein, a circular cutterwill begin rotational movement at approximately 10 to 10000 revolutionsper minute (rpm) of the driveshaft. The device may be translated throughthe lesion to plane and cut the diseased tissue while the OCT imageprovides real time feedback regarding wall and disease characterization,cutter apposition and relative cut depth. During the cutting pass, thetissue may travel through the circular hollow cutter into a tissuereservoir that is distal to the cutter. Upon completing the cuttingpass, proximal controls may be used to articulate the device, returningthe cutter to its shielded position for further delivery and placement.Multiple runs through this procedure may occur to fully treat thedisease.

FIGS. 20A and 20B illustrate one variation of an atherectomy device 200as described. The device includes a cutter 282 rotatable by a driveshaft294 (see FIG. 21) located within an elongated catheter body 201. Thecutter edge, with a comparatively large cross-sectional area, is locatedalong the circumferential surface of the main catheter body 201. Thedriveshaft 294, with a comparatively small cross-sectional area, islocated within the central region of the catheter body. In somevariations, the cutter diameter is at or near the maximum crossingprofile of the main catheter body 201 to maximize cut tissuecross-sectional area and minimize depth of cut. The largecross-sectional area may provide more efficient cutting passes, therebyreducing the time of procedure, and may add a degree of safety byreducing the depth of cut required to achieve comparative luminal gain.

In some variations, at least some portions of the device 200 can behollow. Accordingly, the cutter 282 can cut tissue from the wall of theartery, pass directly through the hollow portions, and be stored in atissue storage area, such as tissue storage area 216.

FIGS. 20A and 20B portray the distal portion of the device in both thenon-activated (FIG. 15A) and activated (FIG. 15B) positions,respectively. In the closed/non-activated position, the cutter 282 isshielded to prevent unintended damage to the inner diameter of ancillarymedical devices and vasculature. In the open/activated position, thecutter 282 is exposed with the tissue packing auger 292 distal of thecutting edge as shown in FIG. 21. In one pull-to-cut configuration for arotational cutter edge catheter embodiment, the distal tip of thecatheter is advanced past the targeted lesion. The catheter is deliveredin the non-activated position where the delivery catheter andvasculature is shielded from the cutter edge. Once the cutter edge ispositioned past the lesion and oriented for optimal tissue removal, thedistal tip assembly is activated to present the cutter edge 282. Thedriveshaft of the catheter is powered to rotate the cutter 282 as it ispassed across the lesion. The rotational motion assists the cutter incutting the targeted tissue. After completing the cutting pass, thedevice is then returned to the non-activated position which assists thecutter in parting off the strip of tissue and packing it into the tissuestorage lumen 216. The device 200 can include an imaging sensor 279 in anotch 277 near the distal end of the device. The imaging sensor 279 canbe an OCT sensor similar to that described above.

Referring to FIG. 21, the driveshaft 294 can be directly connected tothe circumferential cutter 282 and to an auger 292 or Archimedean screw.The driveshaft 294 can thus transmit torque to the cutter 282 whileallowing tissue to pass through the hollow cutter 282 as it is rotated.In this configuration, as the cutter 282 is advanced across a tissuelesion in a pull-to-cut configuration, and the cutter 282 cuts thetissue from the vessel wall. With continued advancement of thecutter/auger assembly, tissue is then passed through the inner, hollowdiameter of the cutter 282. As the tissue advances to the rotating augercomponent 292, the tissue is then cut into segments by the cutting edge299 of the auger component 292 and passed into the tissue storage area216 distal to the auger 292.

The system depicted in FIG. 21 shows the auger component 292 configuredin a helical geometry. However, the auger component can have otherconfigurations. For example, FIGS. 22A-22D show an auger component 293that is capable of shearing tissue segments when rotated in either theclockwise or counterclockwise direction. The auger can be substantiallyT-shaped with two cutting edges 298. Rotation of the auger component 293in either the clockwise or counterclockwise direction would thus causeshearing of tissue. Advantageously, by having two cutting edges 298, theauger component 293 can shear tissue two times per rotation of thedriveshaft 294. The auger component 293 can further include angledsurfaces 297 configured to push cut tissue distally into the tissuestorage area 216. Because the auger component 293 can cut in both theclockwise and counterclockwise directions, it can work even if thedriveshaft oscillates between clockwise and counterclockwise directions,as described above with respect to the driveshaft 421. In thisconfiguration, the cutter edge can be configured for optimal cuttingefficiency and is not limited to traditional, continuously rotatingcutters.

Specifications of the driveshaft may balance flexibility to navigatetortuous anatomy and torsional/tensile/compressive rigidity to drivedistal mechanisms through hard calcified tissues or tight lesions. Ineither the continuously rotating configuration or the oscillatorycutting configuration, the cutter concept can be configured in apush-to-cut configuration where the catheter is advanced to perform thecutting operation. Conversely, the cutter concept can also be configuredin a pull-to-cut configuration where the catheter is retracted toperform the cutting operation. For the illustration purposes only, thedescription herein focuses on the pull-to-cut embodiment, though itshould be clear that push-to-cut variations may be used as well. Commonto all described embodiments, minimal longitudinal motion andtranslational deflection of the tip mechanism such that the tissue entrywindow is mainly defined by the vertical distance from the shearcomponent base 295 to the cutter edge. This may prevent increased tissueinvagination into the exposed tissue entry point with increasedapposition force. Depth of cut will then remain relatively constant atvaried force of engagement between cutter and tissue.

In a pull-to-cut configuration, the cutting edge orientation may be suchthat cutting of tissue is performed with longitudinal movement ofcatheter distal to proximal.

In some variations, the auger mechanism may be configured to function ina continuously rotating system where the auger is configured with ahelical geometry 292. When oscillating the direction of rotation of thedevice driveshaft, the auger 293 may assume a geometry that is capableof shearing tissue segments in either direction of rotation.

As described above, any of these catheters may include imaging,including the atherectomy catheters. The imaging element can provide across-sectional view of vessel wall morphology in the cutting plane.Ultrasound and/or optical imaging technologies may be used. OpticalCoherence Tomography (OCT) is one preferred method of image guidance.The OCT technology currently embodied on prototype devices is capable ofachieving approximate 10 micron lateral resolution and requires fiberoptic assembly diameters below 0.010 inches.

The device may thus include on-board and real time image guidancecapabilities. This capability may require an imaging element, or energyemitting assembly, to be positioned at the distal portion of the devicesuch that local images of the vessel may guide device usage. The distalenergy emitter(s) may be positioned in multiple locations in fixedpositions or embodied in a mating assembly that may translate in aneccentric lumen or in the hollow lumen of the driveshaft. The emittermay send and receive relevant light or sound signals at 90 degrees fromthe catheter axis or at angles up to approximately 50 degrees tovisualize distal or proximal wall features from a fixed position.

The emitting element may be positioned distal and/or proximal to thecutting edge. In a pull-to-cut configuration, proximal placement wouldprovide information during a cutting pass prior to the cutterinteracting with the tissue and, therefore, allow the physician to stopor continue cutting as disease changes in depth and/or position. Distalplacement would also provide guidance regarding cut quality, depth andcutting efficiency.

Furthermore, the data collected at the distal end of the catheter, aftertransmitted and appropriately processed, may drive an automated means ofcutter actuation. Increased amounts of disease detected by the softwaremay automatically increase open distance between the cutter edge and thetip mechanism therefore increasing cut depth. Oscillatory cutter speedsmay be adjusted according to feedback from the imaging system.

Additional details pertinent to the present invention, includingmaterials and manufacturing techniques, may be employed as within thelevel of those with skill in the relevant art. The same may hold truewith respect to method-based aspects of the invention in terms ofadditional acts commonly or logically employed. Also, it is contemplatedthat any optional feature of the inventive variations described may beset forth and claimed independently, or in combination with any one ormore of the features described herein. Likewise, reference to a singularitem, includes the possibility that there are plural of the same itemspresent. More specifically, as used herein and in the appended claims,the singular forms “a”, “and”, “said”, and “the” include pluralreferents unless the context clearly dictates otherwise. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely”, “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Unless defined otherwise herein, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. The breadth of the present invention is not to be limited bythe examples described herein, but only by the plain meaning of theclaim terms employed.

1. (canceled)
 2. A method of crossing a chronic total occlusion, the method comprising: advancing an occlusion crossing catheter into an occluded body lumen of a patient; rotating a rotatable distal tip of the catheter relative to an elongate body of the catheter, wherein the distal tip includes at least one helical blade and an optical coherence tomography (OCT) imaging sensor; imaging a region of the body lumen surrounding the catheter using the OCT sensor on the rotatable tip, wherein the catheter includes at least one marker configured to obstruct imaging from the OCT sensor at least once per rotation of the rotatable tip; and steering the catheter within the body lumen of the patient based upon the OCT image of the body lumen and the marker.
 3. The method of claim 2, wherein the catheter comprises a fixed jog near the rotatable tip, the fixed jog having a fixed orientation relative to the at least one marker, and wherein steering comprises rotating the elongate body of the catheter to orient the fixed jog.
 4. The method of claim 2, wherein the fixed jog comprises an angle of 10 degrees to 45 degrees.
 5. The method of claim 2, wherein the fixed jog comprises an angle of between 20 degrees and 30 degrees.
 6. The method of claim 2, wherein the catheter comprises a bend proximal to the rotatable tip, and wherein steering comprises rotating the elongate body of the catheter to orient the bend.
 7. The method of claim 6, further comprising shaping the bend prior to the advancing step.
 8. The method of claim 2, wherein steering comprises pointing a distal end of the distal tip toward unhealthy tissue imaged by the OCT sensor.
 9. The method of claim 2, wherein the catheter comprises a selective stiffening member, and wherein steering comprises withdrawing and/or inserting the selective stiffening member along the catheter.
 10. The method of claim 2, wherein the catheter comprises a tendon member, and wherein steering comprises bending and/or extending the tendon member.
 11. The method of claim 2, further comprising flushing the imaging sensor region so that it may image the vessel wall.
 12. The method of claim 2, further comprising flushing a fluid through a fluid port adjacent to the OCT imaging sensor.
 13. The method of claim 12, wherein less than 1 mL of fluid is flushed through the port.
 14. The method of claim 2, wherein the OCT imaging sensor comprises an optical fiber coupled with the rotatable tip and configured to rotate therewith, wherein imaging comprises the wrapping the optical fiber around a central lumen within the elongate body as the rotatable tip rotates.
 15. The method of claim 2, further comprising orienting image data taken with the OCT imaging sensor to align the image data with a fluoroscopy image.
 16. The method of claim 2, further comprising displaying the imaged region on a screen.
 17. The method of claim 2, further comprising advancing a guidewire past the occlusion by passing the guidewire through a central lumen within the elongate body of the occlusion crossing catheter.
 18. The method of claim 2, further comprising steering the distal end of the device while rotating the rotatable tip of the device.
 19. The method of claim 2, further comprising advancing the catheter while rotating the rotatable tip to separate tissue in the lumen. 